HSPCs progenitor cells

For clinical and research applications, there are three main sources of human HSCs bone marrow, G-CSF mobilized peripheral blood, and umbilical cord blood (UCB). For clinical purposes, harvests of marrow, mobilized blood, or UCB may be enriched for HSPCs by CD34 (Civin et al. 1996). Such clinical HSPC preparations are a heterogeneous population composed mainly of progenitor cells along with <1% HSCs. 

Sobkow L, Seib FP, Prodanov L, Kurth I, Drichel J, Bornhauser M, Werner C (2011). Prolonged transendothelial migration of human haematopoietic stem and progenitor cells (HSPCs) towards hydrogel-released SDFl. Ann Hematol, 90,865-871. 

At the time of birth and throughout adulthood, the bone marrow is the primary site for hematopoiesis and is the location of most of the HSC population. A small percentage of HSCs are mobilized and found in circulating or peripheral blood (PB). Additionally, other hematopoietic sites function to further differentiate and mature hematopoietic stem and progenitor cells (HSPCs). The thymus differentiates HSPCs into T cells, and the spleen functions to differentiate into B cells (in mice and humans). 

In its natural environment, hematopoiesis resides in a well-defined microenvironment characterized by local geometry (structure and vasculature), by stromal cells (accessory cells of mixed origin), and by an extracellular matrix composed of coUagen-like molecules and proteoglycans, produced by stromal cells (Nielsen, 1999). Thus, it is bkely that hematopoietic stem and progenitor cells (HSPCs) are influenced by accessory cells and the microenvironment they create in several ways. 

A number of perfusion reactors have also been developed for HSPC culture. The greatest success has been achieved with two flat-bed reactor systems a multipass perfusion system, developed at Northwestern University (Koller et al., 1993a), and one with single-pass perfusion, developed at the University of Michigan (Koller et al., 1993b Palsson et al., 1993). Both systems support 10- to 20-fold total cell expansion and 10-fold progenitor expansion, whereas the expansion of primitive cells has only been reported for the second system. 

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